GB2613661A

GB2613661A - Homogenizer control system

Info

Publication number: GB2613661A
Application number: GB2202468.1A
Authority: GB
Inventors: Edwards Michael
Original assignee: Blackswan Graphene Inc
Current assignee: Blackswan Graphene Inc
Priority date: 2021-12-13
Filing date: 2022-02-23
Publication date: 2023-06-14
Also published as: GB2613651A; GB2613657A; GB202201231D0; GB202118020D0; WO2023108265A1; GB202202468D0

Abstract

A homogeniser control system 70 for controlling a homogeniser configured to process a liquid composition comprising suspended material for the purposes of reducing the size of that suspended material to provide a finished product, the control system comprising a processing unit configured, as regards the liquid composition being processed, to receive a measure of particle size of suspended material in liquid composition, receive a measure of pressure of the liquid composition being processed, and can further be configured to control means to adjust one or both of incoming pressure of the liquid processed, the gap in the homogeniser impact head primarily providing the homogenisation action, determined using the received measures. The particle size may be determined by light scattering, or Raman spectroscopy. The liquid composition may be a suspended solid and the homogeniser configured to process that solid to submicron dimensions, or the suspended liquid may be an emulsion and the homogeniser configured to process the ablation to submicron dimensions.

Description

Homogenizer Control System

Background

Graphene is a two-dimensional allotrope of carbon, consisting of sheets of a few atoms thickness in a hexagonal structure. Graphite, the widely used mineral is effectively a crystalline form of graphene, in which layers of graphene are bound together by van der Waals forces. Graphene has attracted considerable interest since its discovery as an isolatable material in 2004. The novel mechanical, thermal and electrical properties of the material suggest a number of uses. Graphene can be produced on a laboratory scale sufficient for experimental analysis, but production in commercial quantities is still a developing area. Other single layered structures such as boron nitride are expected to exhibit similarly interesting properties in the nanotechnology field.

A review of this technology has been compiled by Min Yi and Zhigang Shen and their titled 'A review on mechanical exfoliation for the scalable production of graphene', Journal of Materials Chemistry, A, 2015, 3, 11700 provides an overview of the state of the art regarding graphene production. Bottom-up techniques, such as chemical vapor deposition and epitaxial growth, can yield high-quality graphene with a small number of defects. The resultant graphene is a good candidate for electronic devices. However, these thin-film growth techniques suffer from a limited scale and complex and hence expensive production, and cannot meet the requirements of producing industrially relevant quantities of graphene.

Large-scale production of graphene at a low cost has been demonstrated using top-down techniques, whereby graphene is produced through the direct exfoliation of graphite, sometimes suspended in a liquid phase. The starting material for this is three-dimensional graphite, which is separated by mechanical and/or chemical means to reveal graphene sheets a few atoms thick.

The original technique used by the discoverers of graphene, the "Scotch Tape" method can be used to prepare high-quality and large-area graphene flakes. This technique uses adhesive tape to pull successive layers from a sample of graphite. Based on the graphene samples prepared by this method, many outstanding properties of graphene have been discovered.

However, this method is extremely labor-intensive and time consuming. It is limited to laboratory research and seems unfeasible to scale up for industrial production.

The three-roll mill technique is a method to scale up the Scotch Tape method, using polyvinyl chloride (PVC) dissolved in dioctylphthalate (DOP) as the adhesive on moving rolls which can provide continuous exfoliation. Though the three-roll mill machine is a known industrial technique, the complete removal of residual PVC and DOP to obtain graphene is not easy and brings about additional complexity.

Prof. Jonathan Coleman's group at Trinity College Dublin have developed a high-yield production of graphene by the sonication assisted liquid-phase exfoliation of graphite in 2008. Starting with graphite powder dispersed in specific organic solvents, followed by sonication and centrifugation, they obtained a graphene dispersion. This method of producing graphene is capable of scaling up but one shortcoming is the extremely low graphene concentration (around 0.01 mg/mL) of the suspension produced, which is not necessarily suitable for bulk production.

Additionally, ultrasonic processors can only achieve the high-power density required in small volumes, so it is difficult to scale up this process to achieve any economy of scale. A relevant

disclosure can be found in W02013/010211A1.

Another technique that can produce a high yield while not being as labor intensive, or energy consuming, as the methods describe above, would be the use of shear force techniques. As is well known, graphite layers have a low resistance to shear force which makes graphite a useful lubricant. This has been exploited in a number of techniques which apply shear force to exfoliate graphene from graphite.

Ball milling, a common technique in the powder industry, is a method of generating shear force. A secondary effect is the collisions or vertical impacts by the balls during rolling actions which can fragment graphene flakes into smaller ones, and sometimes even destroy the crystalline nature of structures.

Several improvements to the ball milling technique have been attempted, such as wet ball milling with the addition of solvents, but these techniques still require a very long processing time (around 30 hours) and produce a high number of defects even if suitable for industrial scale, bulk, production. A relevant disclosure can be found in WO 2012117251 Al.

Some shear force production techniques have used an ion intercalation step prior to applying the shear force to weaken the inter-layer bonds. This reduces the energy required to exfoliate the graphite into graphene, but the resulting graphene may be contaminated with residual ions contaminating the finished product, and the process requires additional time and cost which reduces the industrial application of this technique.

More recently fluid dynamics-based methods have emerged for graphite exfoliation. These are based on mixing graphite in a powder or flake form with a fluid to form a suspension, the fluid can then be subjected to turbulent or viscous forces which apply shear stress to the suspended particles. Usually, the fluid is either a liquid of the type often used as a solvent and may include a surfactant mixture tailored to the removable from the finished product.

One method of generating the shear forces is with a high shear, for example rotary mixer. Graphene exfoliation has been demonstrated using a kitchen blender to create shear forces on graphite particles in suspension. This process has been scaled up using commercial high shear mixers comprising rotating blades passing in close proximity to an aperture screen to produce high shear. The graphite particles experience a shear force applied by the fluid due to the difference in velocity of the mixing blades and the static shear screen. A relevant disclosure can be found in W02012/028724A1 and WO 2014/140324 Al.

A further method is the use of a high-pressure homogenizer with a micro fluidizer. The micro fluidizer in this case consists of a channel with a microscale dimension, meaning of around 75pm. Fluid is forced through the channel from an inlet to an outlet using high pressure.

Because of the narrow dimension of the channel, there is a high shear force generated by viscous friction between the walls and the book flow which leads to delamination of the graphite. This method requires very high pressures and the starting graphite must already have been comminuted into the micron size range. A relevant disclosure can be found in W02015/099457.

There exists a need for a graphene production process that can produce graphene using less energy, that can be scaled up to high rates of production without loss of quality of the finished product. Such a process using a preprepared graphite solution, and a homogenizer valve is disclosed within WO 2021/198794, which discloses using areas of high and low pressure within the valve to apply force to the solution, which in turn can break down the graphite in the solution other useful products such as graphene.

Another method using such a homogenize, for produce graphene, can be found in W02018/069722, which discloses an apparatus wherein a pump is used to pump a graphite solution through a fluid conduit, at the end of the conduit the fluid flow is targeted towards the center of a symmetrical impact head, to provide the shear force. wherein the impact head is symmetrical around the axis parallel to the fluid flow. Wherein the impact head can be rotated around the axis of symmetry, so as to reduce the risk of localized wear around the area of impact, thereby extending the operational life-span of the impact head.

It should also be noted that such homogenisers may also be utilized in produce a range of products, such a milk, alcohols, paint and medical solutions, as well as producing different nano structures such as the aforementioned graphene in the form of platelet stacks, while still using the same techniques and apparatus described above. However, each of these different products may require different parameters to produce. Further, the nano structures may require specific parameters to produce the desired structure, for example when producing graphene nano platelets (GNP) they form into stacks of various size, the homogeniser may require different setting to produce stacks at a specific height. However, the above-mentioned homogenisers appear to only measure the initial pressure of the reactants before it enters the homogeniser. Therefore, there is a need to provide homogenisers, with a means on monitoring and adjust parameters to meet the specific requirements of different reactants. Such homogenisers may also require a means of monitoring the product produced by the homogeniser, to ensure such products meet the user's requirements. In particular as high pressures and turbulent flow through a complex geometry are involved there is a need for an adaptive system to enable the highly nonlinear and dynamic systems behaviour to be both monitored and adapted to provide improved process control.

Summary

The present invention provides a homogeniser control system for controlling a homogeniser configured to process a liquid composition comprising suspended material for the purposes of reducing the size of that suspended material to provide a finished product. Wherein the control system comprises a processing unit configured to, in regards to the specific liquid composition being processed, receive a measure of particle size of suspended material in liquid composition, receive a measure of pressure of the liquid composition being processed. This way the control system can confirm the initial status of the reactant, in this case the suspended material, entering the homogeniser. Further, by using the initial particle size, the control system may determine the desire pressure needed to produce sufficient force needed to produce the desired reaction with the homogeniser.

The processor can be further configured, in regards to the liquid composition being processed, to control means to adjust one or both of the incoming pressure of the liquid processed, and/or the gap in the homogeniser head primary providing the homogenisation action determined using one or both of the received measures. This refers to using the control system to adjust the system parameters of the homogeniser to increase the likelihood of a successful reaction. For most homogeniser systems comprise a pressure chamber, configured to receive the liquid composition and to rise the pressure of said liquid composition to a desired level. This pressure increase will apply some force to the liquid which may help start the required reaction, for example when producing an emulsion like milk, the initial pressurisation may start the ablation process. But more importantly will provide a force to move the liquid through the rest of the homogenizer at a specific velocity, in most cases a higher velocity is preferred as this will produce a greater force to break down the suspended material. However, it should be noted that this is not always the case, for example when producing GNP stacks there will be a desired stack height for the final product, and separating each of the platelets may not be desired, therefore there will be a desired force/pressure to produce stacks with a height within a specific range.

From this pressurised chamber the liquid is released into a second chamber wherein a further force can be applied to the liquid to produce the desired homogenisation reaction.

There are different ways such a force can be applied, in some cased the liquid may enter a grinding apparatus, or flow through a centrifuge like device. However, in the preferred embodiment, the homogeniser will utilise an impact head for producing the desired force. Where in the liquid is feed into a conduit that directs the liquid to one or more impact surfaces of the impact head, the force of the impact providing a shear force to the suspended material within the liquid, thereby producing the desired homogenising reaction. After the impact the liquid may then flow out of the homogeniser. In some cased the liquid may flow into channels surrounding the impact head, wherein additional pressure may be exerted onto the liquid to possibly produce more reactions, and wherein the liquid may be directed to further impact surfaces. In such system the control system is configured to adjust the size of these channels by adjust the size of the gap between the impact head and its surroundings, which may comprise a housing or adjacent impact heads. As mention the size of the channel, or in this case the gap forming the channel, will affect the pressure of the liquid as it leaves the homogenising chamber, and may use this pressure to apply additional force on the liquid to increase the chances of a successful reaction and thereby increase the efficiency and yield of the homogenising process.

It should be noted that the determination of the initial size of the suspended material can help determine the amount of force needed to produce the required reaction. In response the control system may set the conduit pressure to a level required to produce the required amount of impact force, further using this information, and/or the initial liquid pressure measurements, the control system can adjust the gap around the impact head to either produce more force, or to ensure the liquid returns to the desired pressure it was under whiles in the pressure chamber. By doing this the control system can ensure that the liquid within the homogeniser is under a constant force, and that there is sufficient force to produce the desired product.

It is noted that the homogeniser may be required to process a wide range of different materials, in some cases the suspended material may comprise a solid which is then suspended within a liquid medium that will carry the solid through the homogeniser, at which point the homogeniser may be configured to break down the solid material, to produce a desired reaction between the solid material and the suspension liquid, to ensure an even distribution of the solid within the liquid medium, or otherwise process the solid to submicron dimensions. Though in other cases the suspended materials may be different liquids that required the homogeniser to combine through a reaction, or to ensure an even distribution, or again process to submicron dimensions. Depending on the material being used, and the desired effect on said material, the control system may be configured to set the parameters of the homogeniser to produce the force/pressure necessary.

In the cases where a solid material is used the control system may also be required to determine the initial size, volume, or other properties that may affect the force needed. For example, the suspended solid may be formed from particles, pieces, or crystals, that may come in various sizes, and depending on the size of the initial solid different amounts of force/pressure will be needed. Therefore, the control system may comprise a means for determining the size of the suspended material, such as a means for preforming spectroscopy. Methods of spectroscopy that may be used include light scattering, which uses the scattering of electromagnetic radiation to determine the atomic make-up of the liquid composition, Raman spectroscopy, which uses the absorption and emission of electromagnetic radiation to determine the atomic scale structure of the liquid composition, this may for example determine the exact atomic structure of a graphene sample, for example the number of graphene layers and the types of edges of the layer which may be 'arm-chaired' or zig-zagged', the spectral analysis may also look into absorption spectrums when the system requires wavelengths outside of light, and IR, frequencies. For example, many nanostructures will have intermolecular bonds that will absorb low frequency waves, typically radio waves, the larger the structure to more the low frequency waves will be absorbed, so this absorption, or other absorption spectrum may be used to determine the initial size of the atomic scale structures present in the liquid composition. Further, it should be noted that in many biological and medical field fluorescent tags are used to mark certain reagents and materials, which give off light under certain conditions, such as exposure to UV, therefore when the homogeniser processes such material it may use an emission spectrum to detect the tags and provide a measure of the amount of the tagged material is present in the suspension.

In the cases wherein the material to be processed in a solid, it is often in the form of a laminar material, such as graphite, which is capable of being delaminated by the homogeniser to form desired atomic scale structures, in this case the delamination of graphite may form different graphene structures, such as GNP, graphene sheets, or nano tubes. However, it is noted that there are other laminar materials that can be processed with a homogeniser, such as hexagonal boron nitride or molybdenum disulphide, or materials may include layered silicates, perovskites, niobates, Mo03, Mn02, Ru02, Ti02, PbI2, MgBr2, MoCl2, RuC13, Mo3S3, NbS3, TiS3, TaS3, Mo3Se3, NbSe3, TiSe3, TaSe3, Mo3Te3, TiTe3 TaTe3 Bi21e3, Bi2Se3, and others materials which normally take the form of 2D layered materials of the form MX2 where M is a transition metal and where X is one of silicon, selenium or tellurium. Such delamination can be performed easily within a homogeniser, additionally different homogenisers can be used to scale the production of such delaminated materials to a desired scale, from small lab samples, to large industrial scales, simply by changing the size of the homogeniser.

Similarly, when using the homogeniser to produce a suspended liquid material, which is most likely the case when using the homogeniser to produce emulsions, such as milk, the control system may be configured to process the ablation, or reaction, of the suspended liquid to submicron dimensions, often through spectroscopy methods such as light scattering. As with the solid materials, these measurements can help determine the initial state of the reactants entering the homogeniser, from which the required pressure, and/or force, to be exerted onto the liquid can be determined. From this the control system may use the control means to adjust the homogeniser parameters to produce the required pressure/force. Such processes may also be used on the final produce to ensure the desired emulsion has formed, or determine that the liquid needs to be processed further.

Regardless, of the type of material being processed, the control system requires a means of adjusting the homogeniser in response to the measurements detailed above. In the preferred embodiment, the means of adjustment would be in the form of a pneumatic system. In particular a pneumatic system configured to move at least a first part of the homogeniser impact head relative to the second part of the impact head, thereby adjust the gap surrounding the impact head. As mention above the change in the gap size may be used to increase the pressure of the liquid after it has impacted the impact head, to help produce additional homogenising reactions. This mechanism may also be used to widen the gap in case of blockages in the homogeniser, which may occur in the gap, especially when using solid materials within the liquid composition. The same system may also be configured to move the impact head relative to the conduit, that directs the liquid to the impact head, as adjusting the travel distance between the pressurised conduit and the impact head may change the amount of force exerted on the liquid when it impacts upon the surface of the impact head. As noted, different reactants require different amounts of force, therefore the control system requires a mean to control and/or determine the amount of force that will be exerted onto the liquid composition, especially in cases where the smallest product is not the most desirable, such as the GNP stacks or nanotubes, as in these cases more force is not necessarily better.

Another, aspect of the claimed control system is the need to measure parameters other than the initial state of the liquid composition. In some cases, the control system may be configured to determine a pressure difference between the incoming liquid, from the pressure chamber, and the outgoing liquid after impacting the homogeniser impact head.

This pressure change may help to determine if the desired reaction has occurred, as in most cases the suspended material should be decreasing in size which in turn may result in the pressure decreasing, therefore meaning the pressure change could be used to determine if the desired product is produced. Alternatively, as mentioned the homogeniser initially set the pressure of the liquid to a desired value to exert force on the liquid, the control system may similarly control the size of the channels the liquid travels through to adjust the pressure of the liquid as the passes through the homogeniser, therefore the control system may be configured to maintain the desired pressure throughout the homogeniser, which would mean adjust the homogeniser so that there is no pressure drop between the different pressure measurements, or at least close to no change between the different points. By maintaining the desired pressure, the liquid is under a constant force which may increase the likelihood of a successful reaction occurring, which in turn may increase the yield of the homogeniser.

Another factor to consider when monitoring the homogeniser, is the temperature of the liquid composition. In many cases, it may be desired for the liquid to be at a higher temperature, as this will give the particles more kinetic energy which may reduce the force needed to break down the suspended material, or to produce the desired reaction. However, this may not always be the case, especially when dealing with bio-chemical materials, as a higher temperature may result in certain materials becoming denatured, additionally if the temperature falls too low this may also adversely affect some bio-chemical materials. In these cases, the control system may need a means of monitoring the temperature of the fluid throughout the homogeniser, or at least within the pressure chamber, to ensure the temperature of the reactants remains within desired parameters, which may be in the form of a desired range, a lower threshold, or an upper threshold, depending of the materials being used.

Further to monitoring the temperature, the control system may comprise a means of controlling the temperature. Such temperature control means may comprise at least one of, a heater, heat sink, radiator or cooler. Wherein the temperature control means may be coupled to the pressure chamber to control the temperature of the liquid composition before it enters the rest of the homogenisers. Some embodiment may also have such temperature control means couple to a region of the homogeniser, that is downstream from the impact head, so that the temperature of the product produce may also be monitored and controlled.

In addition to monitoring the parameters of the liquid produce by the homogeniser, including the pressure, viscosity and/or temperature of the product, the control system may also include an off-set channel, which collects a sample of the product for additional analysis. This further analysis may involve preforming spectroscopy on the sample to determine the content of said sample, this may include light scattering and/or Raman spectroscopy, or looking at absorption/emission spectrums of the product. The result of this analysis may be compared to predetermined results, or the results from the analysis of the initial liquid composition, to determine the content of the product. Any of these data points may be used to determine if the desired reaction has occurred, and may be analysed to determine the yield of the reaction. From here the control system may be configured to detect when the reaction has failed, or when the reaction has reached a desired yield, from this the control system may determine if the product produced is ready to be extracted, or if it needs to be recirculated back into the homogeniser for further processing. In some case this final determination on the state of the product may be indicated to the user. In other cases, the control system may be configured to automatically recirculate the product, or at least part of the product using a diverter, to feed the product back into the homogeniser, when the reaction has failed, or when the yield is below a predetermined threshold.

As mentioned, the control system may monitor certain parameters of the fluid within the homogeniser, and where possible may adjust such parameters to a desired value, this is also true of the fluid with the diverter. More specifically, the control system may be configured to adjust the size of the channels forming the diverted to keep the recirculating liquid at a desired pressure before re-entering the homogeniser. Further, the controller may have a temperature control means comprising at least one of, a heater, heat sink, radiator or cooler, to maintain a desired temperature for the recirculating liquid. However, it is noted that after being pressurised and undergoing the impacts within the homogeniser, it is likely that the product would have an increased temperature after processing, so in the case of a temperature control means for the diverter, said means may only require a cooler, or other means of lowering the temperature of the product.

In some cases, the desired reaction may require a pressure beyond the upper limits of the pressure chamber, whether this limit is the actual limit of the pressure chamber or a safety limit for operating such a chamber, or alternatively the desired reaction for the homogeniser may produce a higher yield if the pressure could be increase beyond such limits. Therefore, the control system may configure a means to produce such increased pressure, in particular the control system may comprise a means to pulse the pressure of the liquid conduit as it enters the homogeniser, or at least the chamber comprising the impact head. Such pressure control means may be couple to an outlet of the pressure chamber, or to the conduit that directs the liquid to the impact head. It should be noted that these pulses may be controlled by the impact head directly, via systems such as pressurised valves, or indirectly by means of oscillation of the pressure chamber or other parts of the homogeniser, such as channels the fluid flows through. In some cases, as the homogeniser operate over time, the regular movements of the homogeniser components form a series of vibrations, which over time may reach a form of resonance that provide the required oscillations to the liquid with the homogeniser to pulse the pressure.

These means of pulsing the pressure provides peak points within the flow of the liquid where the liquid is at a higher pressure, and therefore will experience a higher force within the homogeniser, increasing the likelihood of a successful reaction occurring, and possibly increasing the yield of the reaction. However, in between these peak points will be pint of low pressure, which will likely fall below the pressure produced by the pressure chamber, which will have less chance of a successful reaction, and may even fail to react at all. Such low points within the fluid flow will likely need to be processed again by the homogeniser. That is why it is preferable that such pulsed systems be used alongside the aforementioned diverter, that may recirculate portions of the fluid flow. Moreover, the control system may be configured to synchronize the pressure oscillations and the diverter, especially as the preferred pressure changes will be in the form of regular oscillations. This means that the control system will set the diverted to automatically extract the product produce at the low-pressure points to be recirculated into the homogeniser, thereby reducing the yield loss due to the inconsistent pressure.

In some embodiment the control system may be configured to measure the pressure at different points within the homogenising process beyond the initial pressure chamber and in the gap, or channels, downstream from the homogeniser impact head. More specifically, the control system may be configured to measure the pressure of the fluid immediately before entering the chamber containing the impact head, this may be for example the pressure of the fluid within the conduit, which directs the flow towards the impact surface, as this pressure will determine the velocity of the liquid as it enters the chamber, then using the distance between the impact head and the conduit, the control system may determine the velocity of the liquid at the moment of impact. This in turn may be used to calculate the force exerted by the impact of the fluid onto the impact head. Allowing the control system to ensure that the force exerted is sufficient for the desired reaction. Further, the control system may comprise a means of adjust the force of the impact. This may be in the form of a means to adjust the pressure of the liquid within the conduit, thereby changing the initial velocity of the fluid, and/or and means of changing the distance between the impact head and the conduit, which in turn affects the acceleration of the liquid before the point of impact.

The control system may further comprise a means of measuring the pressure of the fluid as it leaves the impact chamber, in particular a means of determining the pressure of the liquid with the gap between the impact head and their surroundings, as the fluid may have additional force exerted onto it, by increasing the pressure within these gaps. Therefore, the control system may also comprise a means for changing the size of the gaps surrounding the impact head, in doing so the control system can change the pressure of the liquid leaving the impact chamber to a desired level, using the measurements to monitor this change. Additionally, the pressure reading from the gaps may be used as a means of detecting blockages within the impact chamber, at which points the means that control the gap size may move the impact head in a manner that would widen the gap allowing the blockage to be removed. In some cases, the impact head may be configured to use a back pressure build up to remove blockages, the control system may also comprise a means of monitoring and controlling such back pressure As mentioned earlier, the claimed control system may take spectroscopy readings for both the initial liquid composition and for the product produce. By comparing these readings to one another, and/or to known data sets, which may be stored within a memory of the control system, the control system may determine the chemical make-up, and/or structure of the liquids tested. In particular this method may be used to determine the percentage yield of the process. Specifically, using the spectrums of the product to determine the percentage of the product volume that comprises the desired product. From this determination the control system may determine if the yield is within a desired range, or at least above a predetermine threshold. If the product meets the required yield the product can be extract, if not the product can be recirculated into the homogeniser as described above. In some cases, the control system may first determine the amount of suspended material in the initial liquid, from which the control system may determine a maximum yield, from which the desired yield ranges may be determined.

Additionally, the spectroscopy of the initial liquid composition may be use to ensure that there is sufficient suspended material for the process, and determine the size of the initial suspension material as this may affect the amount of force needed for the desired reaction.

Based on the determination of the size of the suspended material, the control system may adjust the components of the homogeniser to produce more, or less, pressure and force in order to produce the desired reaction, such as changing the pressure in the pressure chamber and/or conduit, or by moving the homogeniser impact head to increase or decrease the gap surrounding the impact head, and the distance between the impact head and the conduit.

It is also noted that some of the materials produce by the disclosed homogeniser may be desired for their conductive properties, be it thermal or electrical, for example graphene is often desired for its high electrical conductivity. Therefore, the control system may also comprise a means of measuring the conductivity of the liquid composition at different point in the homogenising process. From which the control system may determine the amount of desired product within the liquid composition at that point. For example, when using a homogeniser to break down graphite into graphene, the control system may be configured to measure the initial conductivity of the liquid, before the homogenising reaction, to set a base line and possible to determine the amount of suspended material within the liquid composition. Then the control system may determine the conductivity of the product produced by the homogenising reaction. The product's results may then be compared to a predetermined threshold, or the initial liquid results, to determine if the reaction was successful, and may also be used to determine how much of the desired product was formed.

Note that in the case of delaminating stakes of nano materials, such as using a homogeniser to shorten stacks of GNP, the previously mention spectroscopy analysis may look very similar for both the initial and desired stacks, due to having the same chemical make-up and similar physical structures. However, in such cases the conductivity of the stacks change, this is why the smaller stacks are often desired over the larger ones, therefore by measuring the conductivity of the fluid the control system may be able to monitor changes within the liquid composition that would be more difficult to determine with spectroscopy alone. It should also be noted that in some cases the desired product may be less conductive than the initial material, but the same process of checking the measurements to pre-determined values, and/or other measurement, would still apply.

It is also noted that the impact head within the homogeniser may become worn over time.

The control system may be able to monitor this wear, for example when taking spectroscopy of the product the control system may be able to determine if debris from the impact head is present within the liquid. Further, some homogenisers may be designed to reduce the risk of such wear on the impact head, in particular the homogenisers may be configured to move the impact head relative to the flow of the liquid composition, to exposed different portions of the impact head to the flow, or the homogeniser may be configured to rotate the impact head, either way the homogeniser has a means of spread the force on the impact head over a wider area. In such homogenisers, the control system may further comprise a means of controlling the movements of the impact head, typically using a pneumatic system to move the impact head laterally and/or to rotate the impact head, either continuously or at predetermined intervals.

In some homogenisers the impact head may rotate freely, in such cases the impact head is usually symmetrical, and therefore may not rotate at first if to liquid flow is distributed evenly. However, once such an impact head becomes worn, there will be an imbalance in the force exerted on the impact head from the liquid flow, this imbalance will cause the impact head to rotate in a manner to more the worn region away from the flow. The control system may be configured to monitor this rotation, using parameters such as the angular velocity and frequency of such rotations to determine how worn the impact head may be. If the determined wear reached a predetermined threshold the control system may be configured to warn the user that the impact head needs replacing, and may even stop the homogeniser entirely until the impact head is repaired.

Drawings Figure 1 depicts an example homogeniser system controlled by the disclosed control system.

Figure 2 depicts an example impact head, and the surrounding housing.

Figure 3 depicts an example of a rotating impact head, and the surrounding housing.

The drawings comprise the following features: 10-First inlet chamber 20-Second inlet chamber 30-First pump 40-Homogenisation chamber 50-Second pump 60-Cooler 70-Computer (representing the control system) 80, 82, 84-Sensors 90-Product 100, 102, 104-Valves 110-Example impact head housing 120-Example impact head 130-Arrows (indicating the movement of the impact head)

Detailed Description

Figure 1 shows an example of a homogeniser system then may be controlled with the disclosed control system 70. This homogeniser comprises two inlet chambers 10,20, the first chamber 10 containing the material that needs to be suspended and the second chamber 20 containing the liquid that will be used to suspend the material from the first chamber 10, when forming the liquid composition. Note that in some systems there may have a third chamber in which the liquid composition is formed before entering the rest of the homogeniser, there may also be additional inlet chambers when the liquid composition comprises more than two materials. It is noted that the control system 70 may be configured to measure the amount of each material entering the homogeniser from each of these inlet chambers 10,20, to determine the chemical make-up of the liquid composition, and may also be used to determine variables such as, total volume of the liquid composition, the percentage volume of the material to be processed, and the expected yield of the process.

In the depicted system, these chambers 10,20 feed materials into an initial pump 30. This pump 30 replaces the pressure chamber mentioned above, as it serves the same purpose of getting the liquid composition to a desired pressure before entering the rest of the homogeniser. It should be noted that this pump 30 may also act as a mixer, forcing the different materials together to form the liquid composition. Though as previously mentioned there may be a separate mixing chamber for forming the composition, and a chamber designed to store the liquid composition at a desired pressure before being pumped into the rest of the homogeniser. It is noted that the cases that use the pump 30 as the mixing/pressure chamber may be preferable as it has fewer components and is therefore simpler to construct and maintain. However, a system with a separate mixing and/or pressure chamber may be preferable, as such systems can store large amounts of liquid composition, regardless of the rate of production of the homogeniser. Also, these mixing/pressure chambers also allow the control system 70 to preform measurements on initial material, and composition, to help set baselines and ranges for the homogeniser's parameters, and allow the control system 70 to take samples of the initial composition for spectroscopic analysis.

From the pump 30, the liquid composition enters the homogenisation chamber 40. The homogenisation chamber 40 contains the apparatus that will exert a force onto the pressurised liquid composition to produce the desired reaction. This apparatus may be in the form of a grinder, or centrifuge. However, in the preferred embodiment the apparatus takes the form of one or more impact heads 120 and their surrounding housing 110, like the one depicted in Figures 2 and 3. In this apparatus the flow of the liquid composition is directed towards one or more impact surfaces of the impact head 120, where upon the liquid will impact the impact head 120, this impact supplies the necessary force to trigger the desired homogenising reaction, note that in some cases the impact head 120 may have several layered surfaces, or there may comprise several layered impact head, allowing the fluid to undergo multiple impacts within this chamber. The liquid composition may also flow off of the impact head 120 and into the walls of the housing 110, again generating additional impacts to exert more force onto the liquid composition. This chamber may also comprise one or conduits, which initial receives the liquid, ensuring that the liquid is at the necessary pressure to propel the liquid at a high enough velocity, so that the force generated by the impact is sufficient to trigger the necessary reaction, before directing the flow of the liquid towards the impact head 120.

It is noted that after the impact the liquid composition will flow down the gaps formed between the impact heads 120 and the housing 110, and also gaps between the impact heads if several are present. These gaps may form one or more channels that may be used to control the pressure of the liquid as it flows through the rest of the homogeniser, it is also noted that these gaps and channels may be shaped to increase the pressure of the liquid composition as it flows through the channels, as this increased pressure will exert a force on the liquid that may trigger further homogenising reactions and thus improve the yield of the process.

In regards to the control system 70, the control system 70 may comprise a means of adjusting different components within the homogenising chamber 40, the control system 70 may also monitor different parameters of the liquid composition as it enters and exits this chamber, such as the liquid's pressure, viscosity, particle size/structure and temperature, as changes in these values may indicate a successful reaction, or in the case of the temperature may indicate parameters that may hinder the reaction, for example if the temperature or pressure is beyond a desired threshold the material within the composition may become denatured. Further, the control system 70 may comprise a means on moving the impact head 120, and/or changing the size of the gaps and channels used to exit the chamber, both of which may change the amount of force exerted onto the liquid as it flows through the homogenising chamber 40. This is typically achieved using a pneumatic system.

In the example shown in figure 2, the pneumatic system would be coupled to the impact head 120, allowing the control system 70 to move the impact head vertically as indicated by the arrows 130. It is noted that in this example the housing 110 surrounding the impact head 120 is sloped so that the vertical moments of the impact head 120 are changing the size of the channels between the impact head 120 and the housing 110, without the need for additional moving parts. It is also noted that moving the impact head vertically, changes the distance between impact head 120 and the source of the liquid, most likely a conduit (not depicted), thereby vary the force exerted when the fluid impacts the impact head 120, as the liquid will have more or less time to accelerate before the impact, changing the velocity of the liquid at the moment of impact. Additionally, the control system 70 may be configured to further control the force of the impact by adjusting the pressure of the liquid as it enters the homogenising chamber 40, which in turn changes the initial velocity of the liquid as it enters this chamber, which again effects the liquid's velocity at the moment of impact.

In addition to adjusting the impact head 120 the control system may similarly use a pneumatic system to instead reposition the conduit, or the housing 110, to again change the force of the impact, or the pressure applied to the liquid as it exits the homogenising chamber 40. The control system 70 may also comprise a means of controlling the temperature of the liquid as it enters and/or exits the homogenising chamber 40, these means may comprise at least one of a heater, radiator, cooler or heat sink, so that the liquid may be kept at within a preferred temperature range. This may especially be the case for the liquid leaving the chamber as the force and pressure applied to the liquid composition may likely cause the temperature of the fluid to increase, as mention this could result in certain biological materials denaturing, and may also cause undesired reactions in certain chemical reactants. Similarly, the user may wish to heat the liquid before entering the homogenising chamber 40, as the increased temperature may increase the likelihood of a successful reaction, due to the reactants having increased kinetic energy prior to impacting upon the homogeniser impact head 120.

From the homogenising chamber 40 the liquid product 90 formed by the homogeniser may flow to one of a pump 50 and/or control valve, at which point the liquid may either be release from the homogeniser system, or the liquid may be recirculated into the homogeniser for further processing. It is noted that in some systems there may be a diverter configured to redirect the liquid to be recirculated. The control system 70 being configured to operate the pump 50, valves and/or diverters in order to direct the flow of the product 90.

In order to determine if the product 90 is ready, or needs to be recirculated, the product 90 may be stored within the pump 50, diverter, or another chamber, wherein the control system 70 may analyse the product 90. Alternatively, the homogenising chamber 40 may have an off-shot channel which collects a sample of the product 90 for analysis. This analysis of the product 90 may include monitoring key parameters, such as particle size, temperature, pressure, conductivity and/or viscosity of the stored product 90, which may be achieved using one or more sensors 80,82,84 coupled to the homogeniser system, which communicate data to the control system 70, ensuring that each of the measured values are either within a desired range, or above a predetermined threshold. Also, the control system 70 may perform as spectroscopy analysis on the product 90, or a sample of the product, using the result of the spectroscopy analysis to determine the chemical makeup, and or atomic scale structures present within the product 90, to determine whether the homogenising reaction was successful, as well as determining the percentage yield of the homogeniser process. This may be achieved by the control system 70 comparing the spectroscopy results, with known results stored within a memory of the control system 70, or comparing the results to the same spectroscopy results of the initial liquid composition. From these results, the control system 70 may determine if sufficient product has been formed. If there is sufficient product in the final liquid composition, then the control system 70 may release the liquid product 90, if not, or if the reaction was not successful, the control system 70 may recirculate the product 90, diverting or pumping the liquid product to an earlier point of the system, either the pressure chamber, homogenising chamber 40, or the conduit of the homogenising chamber 40.

In the depicted system there is a chiller 60 positioned on the path of the recirculated fluid. It is noted that the control system 70 may be comprise means of adjusting parameters of the recirculating product 90. As previously mentioned, the control system 70 may monitor parameters that may affect the likelihood of a successful reaction such as the liquids temperature and pressure. If the desired reaction was not successful, or if the yield was too low, the control system 70 may be configured to not only recirculate the fluid but also to adjust these parameters to increase the yield or the chance of a successful reaction. This may include using temperature controlling means, such as the depicted chiller 60, or other means such as heaters and radiators, to adjust the temperature of the recirculating fluid. It may also include using a pneumatic system to adjust the size of the channel the recirculating fluid travels through to adjust the pressure of the fluid, it is also noted that the pump 50, valve or diverter may also be used to adjust the pressure of the liquid product 90 before it recirculates. Such feature may be necessary when the recirculating liquid goes straight to the homogenising chamber 40, as the product 90 would not enter the initial pump 30, or pressure chamber wherein these parameters were initially set. It is also noted that in the case of a failed reaction, or a reaction with too low a yield, the control system 70 may adjust the thresholds of different parameters to increase the likelihood of a successful reaction, these adjusted thresholds may then be stored within a memory of the control system for use in future processes. However, in such systems there will be some thresholds stored within the control system that can not be altered, for example thresholds due to safety and operational limits, and threshold to prevent denaturing of the material to be processed.

It is also noted that the control system 70 may be configured to automatically recirculate the liquid composition, based on specific conditions. For example, the system may be configured to automatically recirculate the liquid composition a fixed number of times before testing the product 90, with the assumption that each cycle will increase the overall yield, but with diminishing increases each time. In some systems, in order to increase the pressure of the liquid composition, the pressure of the composition may be pulsed. In such cases the pulsed liquid will have both areas of high pressure and low pressure, the high pressure regions will have an increased chance of a successful reaction, while the low pressure regions are more likely to fail to react. In such cases the control system 70 may be configured to automatically recirculate the liquid from the low pressure regions of the flow, this may be achieved by using regular oscillations to pulse the liquid composition at a steady rate, meaning the changes in pressure follow a predictable pattern. At which point the pump 50, valve or diverter, that recirculate the liquid can be synchronised with the regular oscillations to recirculate the low pressure liquid. This will help counteract the negative effect of the low pressure regions, on the yield of the homogeniser process.

It is also noted that in some homogenisers, the one or more impact heads 120 within the homogenising chamber 40 may be configured to rotate, such as the example impact head depicted in Figure 3. This rotation may be driven by another pneumatic system, and/or the impact head 120 may be configured to freely rotate. Regardless of the mechanism the purpose of this rotation is to help prevent wear to the impact head 120, by spreading the force exerted by the liquid composition over a larger area. In the case where the rotation is driven, this rotation may be controlled by the control system 70 using the aforementioned pneumatic system. In the cases where the impact head freely rotates, the control system 70 may monitor the rotation of the impact head 120, for as the impact head becomes worn, these worn portions will create a force imbalance on the impact head thereby changing the rate of rotation of the impact head 120, the control system 70 may detect these changes and alert to user to the severity of the wear on the impact head 120. The control system 70 may also be configured to detect a threshold wear level, wherein once the wear increases beyond such a threshold the control system 70 may stop the flow of the liquid composition to that impact head 120, until it is replaced. The control system 70 may also keep a record of how long each impact head 120 has been in operation, and alert the user to preform maintenance on the impact head once a pre-determined amount of time has passed, this maintenance may include advising the user to replace the impact head entirely.

The depicted system also includes a plurality of valves 100, 102, 104 at various points throughout the system. These valves 100,102,104 can be used to control the flow of the liquid composition through the system. It is noted that these valves 100,102,104 may also be used to create points wherein the flow of the liquid composition can be stored until a desired pressure is reached. These valves 100,102,104 may also provide additional channels, wherein a sample of the liquid composition, or liquid product 90, may be collected for analysis. Additional, around these valves 100,102,104 the system may include sensors for determining the key parameters of the liquid composition, such as particle size, temperature, pressure and viscosity. Wherein the sensors can provide measurements to the control system 70. Such sensors may also be present around the depicted pumps 30,50 and chambers, so that the control system 70 may determine the status of the liquid composition at different points of the homogeniser system.

As mentioned, it is noted that the control system 70 may comprise a memory containing know parameter values, and known spectroscopy results for reactions, reactants and products 90, which the control system 70 may use for comparison during the method described above. In some cases, the user may instead manually enter desired parameters and threshold based on the specific desired reaction. It is also noted that the control system may store within the memory a list of previously used parameters and analysis results so that the control system 70 may determine the best parameters and thresholds to use in order to achieve highest yield for the desired reaction. This way the control system 70 can keep a database of recommended values and dynamically corrected thresholds in order to maximise the efficiency of the homogeniser, by producing a higher yield of the desired product 90.

Therefore, the claimed invention provides a control system 70 that may be incorporated into different homogeniser systems. Wherein the control system 70 can be configured to monitor a homogenisation process, through measurements of key parameters of the liquid to be processed at different stages of said process. The control system 70 may be further configured to use the gather data to dynamically adjust the parameters of the homogenising system to adjust the values of the liquid parameters, thereby increase the likelihood of a successful reaction, in turn improving the yield of the device. This system may also allow a single homogeniser system to be reconfigure for different types of liquid compositions. This will allow a single homogeniser to be used to produce a wide range of products, as the system can be easily reconfigured to meet the requirements of different reactant materials.

Claims

Claims 1. A homogeniser control system (70) for controlling a homogeniser configured to process a liquid composition comprising suspended material for the purposes of reducing the size of that suspended material to provide a finished product (90), the control system (70) comprising: a processing unit, the processing unit being configured, as regards the liquid composition being processed, to: receive a measure of particle size of suspended material in liquid composition receive a measure of pressure of the liquid composition being processed and can further configured, as regards liquid composition being processed, to control means to adjust one or both of incoming pressure of the liquid processed the gap in the homogeniser impact head (120) primary providing the homogenisation action determined using one or both of the received measures.
2. The control system of claim 1 wherein the liquid composition is a suspended solid and the homogeniser is configured to process that solid to submicron dimensions, the particle size being determined by light scattering and/or Raman spectroscopy.
3. The control system of claim 2 were in the suspended solid is selected from laminar materials capable of delamination, such as graphite.
4. The control system of claim 1 when liquid composition is a suspended liquid in the form of an emulsion and the homogeniser is configured to process that ablation to submicron dimensions, the particle size be determined by light scattering.
The control system of claim 4 really liquid composition is milk or a milk product.
6. The control system of any preceding claim wherein the control means is pneumatic and is configured to move the first part of the homogeniser impact head (120) relative to the second part of the homogeniser impact head (120) so as to thereby adjust the gap in the homogeniser chamber (40).
7. The control system of any preceding claim wherein the measure of pressure of the liquid composition is a measure of the pressure drop between incoming liquid composition and outgoing liquid composition, after passing through the homogeniser chamber (40).
8. The control system of any preceding claim wherein the system further measures temperature of the liquid composition the control means adjustment being further determined using that temperature measurement.
9. The control system of any preceding claim wherein the system is configured to recirculate at least a portion of the liquid composition using a diverter, the extent of the diversion being determined by the control system (70).
10. The control system of claim 9 wherein the system is configured to pass the recirculate through a chiller (60) and the extent of the temperature reduction of the liquid composition being determined by the control system (70).
11. The control system of any preceding claim wherein the system is configured to pulse the pressure of the liquid composition entering the homogeniser as controlled directly or indirectly by the control system (70).
12. The control system of claim 11 wherein the pulse in in the form of a regular oscillation.
13. The control system of any preceding claim wherein the pressure of the liquid for use in the control system (70) is measured in the immediate vicinity, such as the entrance of the homogeniser chamber (40).
14. The control system of claim 13 wherein the pressure of the liquid composition for use in the control system (70) is further measured in the immediate vicinity, such as the exit of the homogeniser chamber (40).
15. The control system of any preceding claim wherein the system is configured to monitor the volume fraction of suspended material in the liquid composition and uses this measure in the control system (70).
16. The control system of any preceding claim wherein the system is configured to monitor the conductivity of the liquid composition and use this measure in the control system (70).
17. The control system of any preceding claim wherein the homogeniser impact head (120) or part thereof is configured to be rotatable in use and the system is configured to measure that rotation and use this measure in the control system (70).